Dogs Taught to Sniff Out Prostate Cancer

Posted June 10, 2014

An estimated 233,000 men in the US will be diagnosed with prostate cancer this year. And while current screening methods for the disease can aid in early detection, they are not always accurate. But results of a new study suggest “man’s best friend” might just be able to help.

A new study from Italian researchers found that highly-trained dogs are able to detect prostate cancer in urine with 98 percent accuracy. The results were presented May 18th at the annual meeting of the American Urological Association in Orlando, Florida.

Researchers in Italy enrolled 902 participants and divided them into two main groups: 362 men with prostate cancer, ranging from very-low risk tumors to metastatic disease, and a control group made up of 540 men and women in generally good health or affected by other types of cancer or non-tumor related diseases. All participants provided urine samples.

Two 3-year old, female German Shepherds named Zoe and Liu were trained for about five months at the Italian Ministry of Defense’s Military Veterinary Center in Grosseto using the positive reinforcement “clicker method” and “imprinting,” during which the dogs learn to distinguish certain distinctive scents. Both Zoe and Liu had previously worked as explosive-detection dogs.

During the training, 200 urine samples from the prostate cancer group and 230 samples from the control group were analyzed. The dogs were taught to recognize prostate cancer-specific volatile organic compounds (VOCs) in the samples.

New urine samples were provided for the evaluation phase. The dogs were instructed to sit in front of each sample where they detected the prostate cancer VOC. None of the team members knew which samples were which, except the chief medical veterinary surgeon, who observed from outside the room. The dogs were rewarded when correct identifications were verified.

Dog 1 achieved 100 percent accuracy in detecting samples from prostate cancer patients and 98 percent accuracy in eliminating samples that did not come from a prostate cancer patient.

Dog 2 was close, with 98.6 percent accuracy in detecting prostate cancer and 96.4 percent accuracy in eliminating those that didn’t have the disease. Overall, the dogs had 16 false positives and four false negatives.

“This study gives us a standardized method of diagnosis that is reproducible, low cost and non-invasive,” said lead author Dr. Gianluigi Taverna, chief of the prostatic diseases unit at the Humanitas Research Hospital in Milan, Italy. “Using dogs to recognize prostate cancer might help reduce the number of unnecessary biopsies and better pinpoint patients at high risk for the disease.”

There is no denying a dog’s extraordinary sense of smell. While we have around 5 million olfactory cells in our noses – receptors that detect different odors – dogs have approximately 200 million. It is dogs’ acute ability to trace scents that has made them so attractive to the medical world.